This invention relates to a seat, particularly an aircraft passenger seat, which has a recline linkage which permits ergonomically correct movement of the seat for improved occupant comfort and convenience. A feature of the seat is the placement of the pivot axis of the seat at a level in the region of the hip joint of a typical occupant. Thus, the seat pivots in essentially the same manner and from the essentially the same point as the occupant. This provides greater comfort to the occupant, and prevents or minimizes dishevelment of clothing during travel caused by shirttails being pulled from trousers or skirts as the seat back pivots.
Conventional passenger seats recline in one of several ways. First, the seat bottom may remain stationary, usually at a slight angle, such as 5 degrees from the horizontal, while the seat back is permitted to recline. Such seats are common in "coach" cabins of passenger aircraft, as well as in short haul first class and business class cabins.
Second, the seat back and seat bottom may both pivot, but at the same rate. This has the effect of tilting the seat occupant back, but not allowing the occupant to "unbend" from a normal seating position into a more open and comfortable reclining position. Some office desk chairs use an arrangement similar to this.
As is apparent, if the seat bottom was not moved at all, movement of the seat back from the full upright position would eventually allow the occupant to fully recline once the seat back and seat bottom achieved positions in a similar plane. Such seats are sometimes used in very low density seating configurations, but typically the seat bottom is not moveable.
Ergonomic studies have established that as a seat occupant reclines, i.e., as the seat back moves from the full upright position, greater comfort is achieved if the hips and upper legs are supported, and the occupant is prevented from sliding forward on the seat bottom. This support can be provided by allowing the seat bottom to tilt upwardly as the seat back moves into the recline position. However, simply permitting the seat bottom to tilt upward at the same rate as the seat back reclines keeps the occupant in a close to right angle position. This position is uncomfortable if maintained for long periods of time.
The seat disclosed in this application establishes a ratio of seat back movement to seat bottom movement which enhances occupant comfort by permitting the occupant to unbend as the seat reclines, establishing a position in which the occupant is actually in more of a reclined position, as opposed to merely being tilted from the horizontal.
The seat permits also greater or lesser degrees of recline to be easily achieved by use of interchangeable link bars.